Parlee launched the ESX for 2014, a new aero-road frame. The Massachusetts-based frame builder developed its first aerodynamic road bike after more than two years of CAD modeling, wooden prototyping, and wind tunnel testing.

Before showing the bike to the public, Bob Parlee tested his frame in a wind tunnel, and compared it to two popular bikes from other companies—Cervelo’s R-series, with its Squoval tubes shapes, and Trek’s Madone, which uses Kammtail Virtual Foil shapes. The test revealed, said Parlee, that the new ESX incurs less drag at a wider range of wind angles. An extra benefit: it’s also very quiet as it rolls along the road.

Parlee’s bikes are renowned for their road feel, and once the company had refined the bike’s aerodynamic shaping, it worked to ensure that the ESX would ride as well as its other models. Ultimately, the company arrived at a design that’s both efficient in the wind and—they say—rides very well.

Sections of the frame that are most exposed to the wind—where the head tube connects to the down tube and top tube—are elongated and flattened to decrease drag. The internally routed cables enter the top tube just behind the stem, a location chosen to decrease drag. The tapered steerer accommodates a proprietary spacer that helps create a smooth transition from the steerer to the top tube. The seat tube and post have a flattened, scalloped shape that smooths airflow on the trailing edge of the bike, to further improve aerodynamic performance. The fork, created by Parlee specifically for ESX, has plenty of clearance for wider wheels—currently believed to have superior aerodynamic performance—and has a recess to accommodate a direct-mount front brake caliper (choose either a model from Shimano’s, or on complete bikes with SRAM and Campagnolo set ups, an eeBrake caliper), further improving air flow over the bike’s front end. The bottom bracket has a port for accessing internal wire and cable routing, and accepts the Pressfit 30 standard hardware.

There are currently five sizes of the ESX in production: small, medium, medium/large, large, and extra large (unlike most Parlees, the ESX will not be available in custom geometry). A complete M/L bike weighs about 14.5lbs, the company claims. Frames (with fork and seatpost) cost $5,400. With a SRAM Red 22 group, including eeBrakes, 3T Team Stealth cockpit, Hed Ardennes LT+ wheels, and a Fizik Arione saddle, the bike costs $8,900. Shimano (Di2 and mechanical) and Campagnolo (mechanical only, for now) builds are also available. Other upgrade options include Mavic wheels, or Enve components and wheels.